Plants Love You™ by Cooling Our Homes and Offices

How a green wall can cool a home.

We know that walking under a big shade tree is a good way to cool off on a hot summer day and we are learning more about the real cooling effects of plants. Plants growing on south facing walls can shade the wall and reduce the amount of electricity we need for summer air conditioning.

Plants help us cool down by shading us from the direct sun. Plants also help cool the air when water evaporates on plant leaves – this is called transpirative cooling. Some studies suggest that a mature ivy on a wall can reduce peak energy needed for cooling on a summer day by as much as 28%.

To see how much a green wall really can cool down a building, new work is being done in Toronto at the Green Roof Innovation Testing Laboratory (also called the gritlab) at the University of Toronto, John H. Daniels Faculty of Architecture, Landscape, and Design. This team is looking at how different vines grow on a trellis and how much cooling effect could be counted on from vines. Growing new vines in 2013, the gritlab team measured a cooling range of 6-11%.

New ideas in how to design home and office cooling systems may very well include vines to cool sunny walls!